WebAssembly is supported as well. It has become much faster a few months back when it supported WebAssembly. On my system and using forefox it was 340 knodes/s with asm.js. With WebAssembly it is 600+ knodes/s
Weirdly enough, I was thinking webassembly but I wrote asm.js. I'm very surprised this happened, but apparently it did.
Actually 'WebAssembly' appeared in the title for few minutes, but then it was edited to 'Asm.js'
I was suspecting so. I presume whoever did it followed the link, noticed the engine was using asm.js and not wasm, and thought I was mistaken. But truly what the engine uses depends on the browser and its configuration.